Air conditioning apparatus



Sept. 27, 1965 KELLY 3,275,069

AIR CONDITIONING APPARATUS Filed Feb. '7, 1964 --uJ-u- [I WITNESSES 22 INVENTOR $2M J QV/IM AnThony H, Kelly J BY United States Patent 3,275,069 AIR CONDITIONING APPARATUS Anthony H. Kelly, Upper Arlington, Ohio, assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Feb. 7, 1964, Ser. No. 343,289 3 Claims. (Cl. 165-64) This invention relates to air conditioning apparatus and more particularly to an improved heating element for use in room or unit type air conditioners.

One of the more popular types of air conditioning apparatus on the market today, is the room, or unit, air conditioner which provides for both cooling and heating the air of the room or enclosure in which it is located. The popularity of these units may be attributed to the fact that an occupant of the enclosure may control the environment of the room during winter or summer by providing heat or cooling with a single setting of the controls of the compact unit.

The combination heating and cooling units on the market today, generally fall into two classes. One type of unit is provided with a refrigerating system to cool the air of the enclosure, and a separate electrical heating means provided for warming the air of the enclusure when the thermostat indicates a need for heating. The second type of unit has a refrigerating system operable on the reverse flow principle, in which both heating and cooling of the room air is provided by the refrigerating system. This second type of uint, however, is generally provided with an auxiliary electrical heating element for maintaining proper heating when the outside ambient is below a temperature at which the refrigerating system efficiently operates as a heat pump.

Heretofore, both types of units have made use of heater elements of the open wire resistance type to provide for heating air in the enclosure. As these wire heaters have a relatively small surface area to provide transfer of heat to the air flow in the unit, they are generally designed to operate at a relatively high temperature, usually in the range of 1000 to 1200 F. Operation of the heater element at such high temperatures presents numerous problems.

With the wide use of plastics in the manufacture of self-contained air conditioning units, it is obvious that the heater unit must be located a suflicient distance from the plastic surfaces to prevent warping or cracking of the material. In addition, open wire heaters of this type may not be located in a portion of the unit which is accessible to the user, as contact with these open wire heaters could result in electrical shock should the heater be inadvertently energized. These problems are especially difficult to overcome, in the design of a unit air conditioner, where it is desirable to construct a unit which is compact and lightweight.

It is therefore an object of the present invention to provide a self-contained air conditioning unit having air heating means operating at a relatively low temperature to protect adjacent structure of the unit from excessive heating.

Another object of the invention, is to provide an air conditioning unit having a heating means operable at a relatively low temperature, which means is compact yet provides adequate heat transfer to the air flowing through the unit.

A further object of the invention is to provide an air conditioning unit having a heater element which does not subject the user to the danger of electrical shock, when the heater is located in a portion of the unit readily accessible to the user.

These objects of the invention, as well as other ob- 3,275,069 Patented Sept. .27, 1966 jects which will become apparent as the description proceeds, are achieved by providing air conditioning apparatus having a heating means of the sheathed tube resistance type. The sheathed tube resistance heater is further provided with a plurality of radially outwardly extending heat transfer surfaces or fins.

The resultant finned tube heater is so constructed, and so located in the air flow, that operation of the heater element through a relatively low temperature range provides adequate heat transfer to the air passing thereover.

For a better understanding of the invention reference should be had to the accompanying drawings, wherein:

FIGURE 1 is a top plan view showing a room air conditioner having portions of the structure broken away to better show details of the invention; and

FIGURE 2 is a front elevational view of the air conditioning unit of FIGURE 1, again having portions of the structure broken away for clarity in showing the invention.

Although the principles of the invention are broadly applicable to self-contained air conditioning units, the invention has been herein illustrated as employed in a window mounted unit, and will be so described.

Referring to the figures, especially FIGURE 1, there is shown a self-contained air conditioning unit 10 having a housing 11 containing the various components of a refrigerating system. The housing 11 is divided by partition 12 into outside and inside air compartments. The outside air compartment contains a refrigerant compressor 13, an outside heat exchanger, or condenser 14, fan 16 and fan motor 17. The inside compartment contains an inside heat exchanger or evaporator 18, and centrifugal blower 19.

Referring particularly to the inside, or room air portion of the unit 10, it should be noted that a horizontally disposed partition 21 divides this portion of the unit and provides a means for ducting air flow through the unit. As best shown in FIGURE 1, an inlet opening 22 is provided in the housing 11 below the partition 21 to provide for entry of air from the enclosure to the housing. The face of the housing 11 above the partition 21 is also open to the enclosure, to provide an outlet opening 23 for discharge of conditioned air from the housing to the enclosure.

As best shown in FIGURE 2, the inlet opening 22 is covered by a louvered member 24 which is removable to permit access to a filter member 26 located in the inlet opening. The air filter 26 serves to collect dust and dirt particles from the incoming air, and therefore must be removed from time to time for cleaning and servicing.

The outlet opening 23 is also provided with a suitable grill work, or louvered member 27 which in addition to providing an attractive appearance, may also be designed to direct the flow of conditioned air from the unit 10 in a manner to effectively distribute the air throughout the enclosure.

A control panel 28 completes the interior face wall of the unit 10, and has located adjacent thereto the various electrical components which are required to activate the air conditioning components of the unit 10. As the various switches, thermostats, etc. used to control systems of this type are well known in the art, these elements will not be described in detail as they form no part of the present invention.

As best shown by the arrows in FIGURE 1, air from the enclosure flows through the louvered member 24 into the inlet opening 22 when the centrifugal blower 19 is operating. The flow of air then passes through the blower 19, over the upper surface of the partition 21 and is discharged over the heat exchanger 18 and through the outlet opening 23.

In practicing the present invention, a heater element 29 of novel construction is disposed in the air flow near the inlet opening 22. The heater element 29 is of the sheathed type having an outer tubular member 31 and a helically wound fin member 32 extending radially outwardly from the tubular member. The heater element 29 has a mounting plate 33 attached to a divider wall 34 which extends from the partition 12 to the front opening 22 of the unit. A pair of connector terminals 35 and 36 extend through the divider wall 34 and are connected across a voltage source controlled by the control system of the unit. The heater element 29 is further connected to the housing 11 by a bracket 37 which serves primarily to support the heater to prevent damage due to excessive movement during shipping.

The internal structure of the sheathed heater element 29 may be constructed in the usual manner, having the terminals 35 and 36 attached to a resistance wire which is housed within, but isolated from, the tubular member 31 by magnesium oxide, or similar material effective to electrically insulate the resistance wire from the tubular member 31, and to provide good heat transfer to the member.

In constructing the heater element 29, the element is first bent into a hair pin shape, and then rolled into a convolute shape, as best shown in FIGURE 2.

The convolute shape of the heater 29 is disposed with its central axis in the direction of air flow and in effect provides a pair of convolute elements over which the air flow must pass. The large surface areas provided by the construction and shape of the heater 29, together with the double passing of air provided by the arrangement, serve to greatly increase the heat transfer to a given quantity of air flow over that obtained by prior art heaters. It is obvious that, by so mounting and so constructing the heater element 29, the greater portion of the tubular member 31 and the fin members 32 are in heat exchange relation to the inlet air flow, which permits operation of the heater at a relatively low temperature which is harmless to nearby plastic parts.

In the structure shown, satisfactory results have been obtained by operating the heater unit at a maximum tem perature of 600 F. as measured on the tubular member 31. However, this maximum temperature might, if desired, be varied to some degree, should the heater element 29 be used for auxiliary heating, as would be the case in a heat pump application.

From the foregoing, it should be evident that the present invention provides an air conditioning unit having a heater element operable at a lower temperature than heretofore. The lower operating temperature of the heating element 29 is rendered feasible by the large surface area which the heater element of the present invention presents to the air flow through the unit. The large surface area is brought about by the invention as described above in detail, and which is effective to protect the various plastic parts of the air conditioning unit by providing for such low temperature operation.

In addition, should the heater element be activated dur- 4 ing removal or replacement of the filter element 26, there is no danger of electrical shock to the user, as the resistance wires of the heater element 29 are protected and insulated by tubular member 31.

While the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes andmodifications without departing from the spirit thereof.

I claim as my invention:

1. Room air conditioner apparatus for conditioning the air of an enclosure, comprising:

a refrigerating system,

a housing for said refrigerating system,

said housing having an inlet opening for entry of air from said enclosure into said housing and an outlet opening for discharge of conditioned air from said housing to said enclosure,

air translating means disposed in said housing for causing a stream of air to flow into said inlet opening and discharge from said outlet opening,

said refrigerating system having a heat exchanger disposed in the path of said air flow,

a sheathed electric resistance heating element being shaped from a single continuous tubular member first bent back upon itself at its center and then wound in an opening-spiral from said center to the terminal ends of the two legs to form each of the said legs of said heating element into a spiral paralleling the other said leg,

said element being disposed in said inlet opening with said spiral form center generally centrally located in said opening and said terminal ends located out of said inlet opening,

said legs lying in successive planes transverse to the direction of said air flow path through said inlet openmg.

, 2. Room air conditioner apparatus according to claim 1 wherein:

said tubular member carries fin means for promoting heat transfer from said heating element to said air flow.

3. Room air conditioner apparatus according to claim 1 wherein:

said spiral form element is disposed in a location closer to the air entry face of said inlet opening than to said air translating means, and

said housing includes plastic louver means disposed to cover said air entry face.

References Cited by the Examiner UNITED STATES PATENTS 2,594,101 4/1952 Volker 219--370 2,672,734 3/1954 Ditzler et a1 -29 3,029,332. 4/1962 Cotts 165-64 3,199,580 8/1965 Vaughn 165-64 ROBERT A. OLEARY, Primary Examiner.

CHARLES SUKALO, Examiner. 

1. ROOM AIR CONDITIONER APPARATUS FOR CONDITIONING THE AIR OF AN ENCLOSING, COMPRISING: A REFRIGERATING SYSTEM, A HOUSING FOR SAID REFIGERATING SYSTEM, SAID HOUSING HAVING AN INLET OPENING FOR ENTRY OF AIR FROM SAID ENCLOSURE INTO SAID HOUSING AND AN OUTLET OPENING FOR DISCHARGE OF CONDITIONED AIR FROM SAID HOUSING TO SAID ENCLOSURE, AIR TRANSLATING MEANS DISPOSED IN SAID HOUSING FOR CAUSING A STREAM OF AIR TO FLOW INTO SAID INLET OPENING AND DISCHARGE FROM SAID OUTLET OPENING, SAID REFRIGERATING SYSTEM HAVING A HEAT EXCHANGER DISPOSED IN THE PATH OF SAID AIR FLOW, A SHEATHED ELECTRIC RESISTANCE HEATING ELEMENT BEING SHAPED FROM A SINGLE CONTINUOUS TUBULAR MEMBER 